			(function(doc, win) {
				var docEl = doc.documentElement,
					isIOS = navigator.userAgent.match(/iphone|ipod|ipad/gi),
					dpr = isIOS ? Math.min(win.devicePixelRatio, 3) : 1,
					dpr = window.top === window.self ? dpr : 1, //被iframe引用时，禁止缩放
					dpr = 1, // 首页引用IFRAME，强制为1
					scale = 1 / dpr,
					resizeEvt = 'orientationchange' in window ? 'orientationchange' : 'resize';
				docEl.dataset.dpr = win.devicePixelRatio;
				if(navigator.userAgent.match(/iphone/gi) && screen.width == 375 && win.devicePixelRatio == 2) {
					docEl.classList.add('iphone6')
				}
				if(navigator.userAgent.match(/iphone/gi) && screen.width == 414 && win.devicePixelRatio == 3) {
					docEl.classList.add('iphone6p')
				}
				var metaEl = doc.createElement('meta');
				metaEl.name = 'viewport';
				metaEl.content = 'initial-scale=' + scale + ',maximum-scale=' + scale + ', minimum-scale=' + scale;
				docEl.firstElementChild.appendChild(metaEl);
				var recalc = function() {
					var width = docEl.clientWidth;
					if(width / dpr > 750) {
						width = 750 * dpr;
					}
					docEl.style.fontSize = 100 * (width / 750) + 'px';
				};
				recalc()
				if(!doc.addEventListener) return;
				// win.addEventListener(resizeEvt, recalc, false);
			})(document, window);